Pharmacokinetics and pharmacodynamics of intravenous esomeprazole at 2 different dosages in dogs.

Background: Although the demand for esomeprazole is increasing in veterinary medicine, the pharmacokinetics (PK) and pharmacodynamics of esomeprazole have been described in only a few studies. Objective: To determine the PK of 0.5 and 1 mg/kg esomeprazole administered IV q12h and to investigate its effects on intragastric pH in healthy dogs. Animals: Six adult Beagles. Methods: Open-label, randomized, and crossover design. The dogs received 0.5 or 1 mg/kg esomeprazole IV q12h for 48 hours. Plasma concentrations of esomeprazole were measured by high-performance liquid chromatography-tandem mass spectrometry. Intragastric pH was determined using the Bravo pH monitoring system and recorded as mean percentage time (MPT) for which pH was >= 3 and >= 4 for 24 hours in each group. Results: The peak plasma concentration and area under the curve from the time of dosing to the last measurable concentration in the 1 mg/kg group were higher than those in the 0.5 mg/kg group. However, when the dosage normalized, intergroup differences were not significant. The MPTs for which intragastric pH was >= 3 and >= 4 for 48 hours were 88% +/- 7% and 81% +/- 9% for the 0.5 mg/kg group and 90% +/- 9% and 85% + 11% for the 1 mg/kg group, respectively, with no significant intergroup differences. Conclusions and Clinical Importance: The pharmacokinetic parameters and acid suppressant effect for 0.5 and 1 mg/kg esomeprazole were not significantly different. Furthermore, the efficacy of esomeprazole 0.5 mg/kg IV q12h was sufficient to increase intragastric pH in Beagles.